With the continuous development of information technology, a DWDM (Dense Wavelength Division Multiplexing, dense wavelength division multiplexing) technology provides an efficient approach to a point-to-point optical fiber transmission with a large capacity. In an all-optical communication network, the DWDN technology is used on a trunk line to extend capacity, an optical add-drop multiplexer (OADM, Optical Add-Drop Multiplexer) and an optical cross connect (OXC, Optical Cross Connect) are used as a cross node, and fiber to the home (FTTH, Fiber To The Home) is realized by an optical fiber access technology. The OXC and the OADM are core technologies of the all-optical network, and cores of the OXC and the OADM are an optical switch and an optical switch array. A MEMS (Micro-Electro-Mechanic System, micro-electro-mechanic system) optical switch may include a 2D-MEMS (2-Dimensions Micro-Electro-Mechanic System, 2-dimensions micro-electro-mechanic system) optical switch and a 3D-MEMS (3-Dimensions Micro-Electro-Mechanic System, 3-dimensions micro-electro-mechanic system) optical switch. A large-scale switch array can not be realized by the 2D-MEMS optical switch because of unbalance insertion losses of channels. A very large-scale switch array can be realized by the 3D-MEMS optical switch because of a small distance between ports of the 3D-MEMS optical switch. Therefore, the 3D-MEMS optical switch can be used to realize a large-capacity OXC node, which can be applied to a large-capacity optical switching field.
In the 3D-MEMS, a micromirror is rotated to deflect the optical path, therefore switching between optical paths. However, the micromirror can not be rotated to an optimal location steadily and rapidly because of some factors such as inertia and vibration, and therefore the insertion loss of the 3D-MEMS optical switch can not reach an optimal state. In a conventional technology, a power detection module is added at an input port and an output port of an optical fiber. A closed loop feedback mechanism is formed by comparing an input power with an output power and feeding back a comparison result to the micromirror, to control the micromirror, thereby calibrating the micromirror to be in the optimal state and minimizing the insertion loss of the 3D-MEMS optical switch.
In the 3D-MEMS optical switch according to the conventional technology, an optical power detection module of the optical switch is disposed separately from a core optical switch module. As shown in FIG. 1, the optical power detection module of the optical switch is disposed at an input/output port of an optical fiber. An input port of each path is connected with a 1×2 coupler, and two output ports of the coupler can provide light which is split on demand, such as 5%:95%, 2%:98% or 10%:90%. A PD (power detector, power detector) is connected to a port having a smaller coupling ratio, to detect optical power. A port having a larger coupling ratio is connected to the core optical switch module. All couplers and the PDs at the input port are placed in the same optical power detection module, and similarly, an optical power detection module is formed at the output port.
The conventional technology has defects as follows: the power detection modules are added at the input port and the output port of the optical fiber, and the core optical switch module is disposed separately from the optical power detection module, both the core optical switch module and the optical power detection module are connected to a master control board via data lines, and the length of the data line may limit a communication rate between the optical power detection module and the core optical switch module, thereby prolonging a calibration and stabilization time for a micromirror; a large number of couplers and PDs are required when a large-scale 3D-MEMS optical switch is realized, so that the volume of the optical power detection module becomes very large, which does not facilitate actual usage; and cost is increased with an increase in the scale of 3D-MEMS due to one coupler and one PD arranged in each path.